Lecture 3 Flashcards
propulsive movement
push contents forward through the digestive tract
mixing movement
promote breakdown and facilitate absorption across the digestive wall
mechanical digestion
physical mixing and churning that breakdown large masses of food into smaller masses of food
chemical digestion
using enzymes to break bonds of large molecules into small molecules
why is it important to break down food physically
to increase surface area for enzyme action
main enzyme in saliva
amylase (alpha 1-4 bonds in starch)
other components of saliva
electrolytes, lingual lipase
purpose of mucus
lubrication
protect gut wall from digestive enzymes
order of layers
- lumen
- mucosa
- muscularis externa
- serosa
mucosa
innermost mucous membrane layer
produces and releases secretions needed for digestion
lymphoid tissues protect the body
submucosa
connective tissue w/blood vessels, lymphatic vessels, nerves, and lymphoid tissue
muscularis externa
two layers of smooth muscles
- longitudinal and circular
- responsible for GI motility
serosa
connective tissue
outer cover that protects the GI tract
bolus components
food and saliva
_____ grinds and mixes food w/gastric juice to form _____
antrum, chyme
how does volume affect motility of the stomach
when full, motility and emptying is stimulated
fluidity affect motility of stomach
when more broken down, chyme is easier to move, and emptying will be stimulated
how do high levels of fat, acid, distension of small intestine affect motility of the stomach
inhibits emptying until the small intestine can process more
how does stress impact motility of the stomach
inhibits motility and emptying via sympathetic nervous system
cardia
- part near esophagus
- contains cardiac glands
pylorus
- part priximal to pyloric sphicter
- contains pyloric glands
fundus/body
- between cardia and pylorus
- contains fundic/gastric glands
cardiac glands
- mainly mucus cells
- some entereoendocrine cells interspersed
pyloric glands
- mucus cells
- entereoendocrine cells (g and d cells)
